Ocular administration of drugs is primarily associated with the need to treat ophthalmic diseases. The eye is the most easily accessible site for topical administration of a medication. Ophthalmic preparations are sterile products essentially free from foreign particles, suitably compounded and packaged for instillation into the eye. They are easily administered by the nurse or the patient himself, they have quick absorption and effect, less visual and systemic side effects, increased shelf life and better patient compliance.
Drugs may be delivered to the eye through the application of four primary modes of administration: systemic, topical, intravitreal, and periocular. Topical administration is generally considered the preferred route for the administration of ocular drugs due to its convenience and affordability. Drugs applied in this manner can be in multiple forms, including solutions, ointments and suspensions.
Drug absorption occurs through corneal and non-corneal pathways. Most non-corneal absorption occurs via the nasolacrimal duct and leads to non-productive systemic uptake, while most drug transported through the cornea is taken up by the targeted intraocular tissue. Unfortunately, corneal absorption is limited by drainage of the instilled solutions, lacrimation, tear turnover, metabolism, tear evaporation, non-productive absorption/adsorption, limited corneal area, poor corneal permeability, binding by the lacrimal proteins, enzymatic degradation.
The objective of ocular medication delivery is maximizing the amount of medication that reaches the ocular site of action in sufficient concentration to produce a beneficial therapeutic effect. This is determined by the dynamics of ocular pharmacokinetics: absorption, distribution, metabolism and excretion.
Aqueous solutions are most commonly used for the eye. They are the least expensive medications and interfere least with vision. Some commonly used ocular medications are topical anesthetics, mydriatics and cycloplegics, medications used to treat glaucoma, anti-infectives, corticosteroids and non-steroidal anti-inflammatory drugs.
EP 0999825 B1 discloses a topical ophthalmic composition comprising one or more galactomannan(s) and one or more borate compound(s), wherein the galactomannan and the borate compound are contained in the composition in concentrations effective to create a gel or partial gel when the composition is administered to an eye.
U.S. Pat. No. 7,491,383 B2 discloses compositions comprising a therapeutic component and an efficacy enhancing component that enhances the pharmacokinetic disposition of the therapeutic component. The therapeutic component and the efficacy enhancing component may form a complex.
Although each of the patents above represents an attempt to provide stable solutions for ophthalmic administration, there still remains the need in the art for alternative formulations providing as well adequate chemical and physical characteristics and improved patient compliance. In particular, there is a need for formulations that are free from preservatives to be provided in a multiple use container and provide efficient dosing of the solution to the patient, without wastage.